Sealed & Ported. How big of a difference??

I want to go ported. But i dont think i have enough room!!! will i be missing out alot, if i settle for sealed instead of ported? I have 2 infinity 1230w's and this is my first system, i want it to sound nice. I listen to rap.

Also if someone wants to make me plans, I.M. me on aim at ForzaMS05 if u dont have aim, email me at [email protected] !!! I will pay!!